An experimental facility was constructed and instrumented to conduct heat transfer experiments and flow visualization. The experimental facility is a 1/5-scale model of a full-scale two story building with aspect ratio (H/L) of 0.625. Natural convection experiments were conducted with hot and cold end walls with the rest of the enclosure insulated. Air was the working medium inside the experimental facility. The Grashof number of the flow was ~ 108. Smoke flow visualization and PIV were conducted for the flow field inside the experimental facility. Heat transfer results obtained agreed fine with the results reported in the literature. Smoke visualization and PIV techniques showed the existence of thin boundary layer next to the isothermal walls and stationary core inside the enclosure. The flow was two dimensional as proved by the temperature measurement, smoke visualization, and PIV results. PIV measurements showed the existence of reversing loops next to the top and bottom of the enclosure. The PIV technique worked well with natural convection flow with olive oil droplets of 1 – 3 mm used as seeding particles PIV measurements.